[BenjiWiebe]

I think there's some confusion in this thread. GGP talks about distributing the one time pad via the numbers station. GP (rightly) says that's a stupid idea.

The numbers station should be transmitting a message encoded with a one time pad. The one time pad itself should be physically given in person to the spies who you want to communicate with.

[bell-cot]

Or, if one is uncertain whether to trust the courier between you and your spy - one can send two different one time pads by two different couriers. If the spy is trained to xor those pads together before using, an enemy must intercept both pads to be able to read your messages.

There are many variants on this, including pads which you hope your enemy will intercept.